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Sinodonty and Sundadonty

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Distribution of sinodonts and sundadonts in Asia, shown by yellow and red. Also shown are australoids, indicated by A, and negritos, indicated by N.[1]

In anthropology, Sinodonty and Sundadonty are two patterns of features widely found in the dentitions of different populations in East Asia. These two patterns were identified by anthropologist Christy G. Turner II as being within the greater "Mongoloid dental complex".[2] Sundadonty is regarded as having a more generalised, proto-Mongoloid morphology and having a longer ancestry than its offspring, Sinodonty.

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Tsunehiko Hanihara (1993) believed that the dental features of Aboriginal Australians have the characteristic of high frequencies of "evolutionarily conservative characteristics," which is called the "proto-sundadont" pattern.[3]

C.G Turner II shows with his analysis of 2016 that sundadonty is the proto-Mongolid dental morphology and is not connected to the Australoid dental morphology. He also shows that sinodonty is predominant in Native Americans.[4]

Turner defined the Sinodont and Sundadont dental complexes in contrast to a broader Mongoloid dental complex.[5] Hanihara defined the Mongoloid dental complex in 1966. In 1984, Turner separated the Mongoloid dental complex into the Sinodont and Sundadont dental complexes.[6]

Ryuta Hamada, Shintaro Kondo and Eizo Wakatsuki (1997) said that, based on dental traits, Mongoloids are separated into sinodonts and sundadonts, which is supported by Christy G. Turner II (1989).[7][8]

In 1996, Rebecca Haydenblit of the Hominid Evolutionary Biology Research Group at Cambridge University did a study on the dentition of four pre-Columbian Mesoamerican populations and compared their data to "other Mongoloid populations".[9] She found that "Tlatilco", "Cuicuilco", "Monte Albán" and "Cholula" populations followed an overall "Sundadont" dental pattern "characteristic of Southeast Asia" rather than a "Sinodont" dental pattern "characteristic of Northeast Asia".[9]

The upper first premolar has one root (whereas the upper first premolar in Caucasians normally has two roots), and the lower first molar in Sinodonts has three roots (3RM1) whereas it has two roots in Caucasoid teeth.[10][5]

Today, the largest number of references to Turner's work are from discussions of the origin of Paleo-Amerindians and modern Native Americans, including the Kennewick Man controversy. Turner found that the dental remains of both ancient and modern Amerindians are more similar to each other than they are to dental complexes from other continents, but that the Sinodont patterns of the Paleo-Amerindians identify their ancestral homeland as north-east Asia. Some later studies have questioned this and found Sundadont features in some American peoples.

^Hanihara, Tsunehiko. (1993). Craniofacial Features of Southeast Asians and Jomonese: A Reconsideration of Their Microevolution Since the Late Pleistocene. Anthropological Science, 101(1). Page 26. Retrieved March 8, 2018, from link to the PDF document.

^Díaz, E. et al. (2014). Frequency and variability of dental morphology in deciduous and permanent dentition of a Nasa indigenous group in the municipality of Morales, Cauca, Colombia. In Colombia Médica, 45(1). Pages 15–24. Retrieved December 14, 2016, from link.

^ abKimura, R. et al. (2009). A Common Variation in EDAR Is a Genetic Determinant of Shovel-Shaped Incisors. In American Journal of Human Genetics, 85(4). Page 528. Retrieved December 24, 2016, from link.